凝胶-燃烧法合成新型宽激发带蓝色发光材料Sr_3MgSi_3O_(10):Eu^(2+)

SYNTHESIS OF NOVEL BLUE EMITTING PHOSPHORS Sr_3MgSi_3O_(10):Eu^(2+) WITH BROAD EXCITATION BAND BY THE GEL-COMBUSTION METHOD

采用凝胶–燃烧法在活性炭弱还原气氛中成功合成新型宽激发带蓝色发光材料Sr3MgSi3O10:Eu2+。用X射线粉末衍射仪及荧光分光光度计等分析和表征合成样品的物相结构和发光性质。结果表明:所合成的Sr3MgSi3O10:Eu2+的晶体结构与Sr2MgSi2O7的相似,同属四方晶系;激发光谱分布在250～450nm的宽带范围,主激发峰位于366nm处,次激发峰位于394nm处,可以被InGaN管芯产生的350～410nm辐射有效激发;在366nm近紫外光的激发下,发射光谱为一宽带,最大发射峰位于466nm附近,是典型Eu2+的4f5d–4f跃迁导致的。研究发现:Sr3MgSi3O10:Eu2+蓝色荧光粉的发光强度随还原温度的升高而增强;随Eu2+摩尔(下同)浓度的增加逐渐加强,当Eu2+为10%时,发光强度达到最大值,而后随Eu2+浓度的增加而减小,发生浓度猝灭。根据Dexter能量共振理论,该浓度猝灭系Eu2+的电偶极–电四极相互作用所致。

The novel blue emitting phosphor Sr3MgSi3O10：Eu2＋ with broad excitation band was synthesized by the gel-combustion method in a weak reductive environment. The phase structure and luminescent properties of the as-synthesized phosphors were characterized and analyzed by the X-ray diffraction and fluorescence spectrophotometer. The results show that Sr3MgSi3O10：Eu2＋ phosphors possess the tetragonal crystal structure similar to that of Sr2MgSi2O7. The excitation spectrum of Sr3MgSi3O10：Eu 2＋ is a broad band in the range of 250–450 nm,and the main peak is at 366 nm and the secondary peak is at 394 nm. Therefore,this phosphor can be excited efficiently by InGaN chip in the range of 350–410 nm. The emission spectrum excited by 366 nm shows a wide band with the main peak at about 466 nm,which is ascribed to the typical transition from 4f 5d to 4f of Eu2＋. It is found that the luminescent intensity of Sr3MgSi3O10：Eu2＋ phosphors increases with the increase of reductive temperature. Moreover,the luminescent intensity increases with the increase of Eu2＋ content （in mole,the same below）,and reaches the maximum when the content of Eu2＋ is 10%,and then decreases with the further increase of Eu2＋ content,namely the concentration quenching occurs. The concentration quenching is caused by the interaction of electric dipole-electric quadrupole of Eu2＋ according to the Dexter theory.